a. Field of the Invention
The invention relates generally to an optical lens, and more particularly to an optical lens having at least one movable lens group.
b. Description of the Related Art
Recent advances in technology have led to the development of various types of optical lenses, such as a surveillance camera disclosed in U.S. patent publication no. 2015/024167 (briefly referred to as '167 application) or U.S. Pat. No. 4,844,599 (briefly referred to as '599 patent).
'167 application discloses that multiple lens groups of a zoom lens with a high zoom ratio need to move in unison with each other to perform zooming and focusing operations. This, however, may increase design complexity, constrain manufacturing tolerances, require an elevated level of precision, and therefore increase fabrication costs of the zoom lens.
Further, '599 patent discloses an aperture stop that may move during zooming and focusing to allow for greater design freedom. However, in practical application, a movable aperture stop is normally realized by a complicated mechanism that may reduce manufacturing yield and increase fabrication costs.